﻿/****************************** Module Header ******************************\
 * Module Name:  CaptchaHelper.cs
 * Module Version:  1.0.0 (2013-7-2)
 * Copyright (c) AnyEB.Com (14507247@qq.com)
 * 
 * This class is used to draw captcha image.
 * 
 * This source is subject to the GPL License.
 * See http://www.gnu.org/licenses/gpl.html.
 * All other rights reserved.
 * 
 * THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, 
 * EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED 
 * WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
\***************************************************************************/
using System;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

namespace UCL
{
    /// <summary>
    /// 验证码
    /// </summary>
    public class CaptchaHelper
    {
        private static CaptchaHelper instance;
        public static CaptchaHelper Instance
        {
            get
            {
                if (instance == null) instance = new CaptchaHelper();
                return instance;

            }
        }

        public string GenerateCheckCode()
        {
            int number;
            char code;
            string checkCode = String.Empty;
            System.Random random = new Random();
            for (int i = 0; i < 4; i++)
            {
                number = random.Next();
                code = (char)('0' + (char)(number % 10));
                checkCode += code.ToString();
            }
            return checkCode;
        }

        public byte[] GetCheckCodeImage(string checkCode)
        {
            if (checkCode == null || checkCode.Trim() == String.Empty) return null;

            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);
            Graphics g = Graphics.FromImage(image);

            //生成随机生成器
            Random random = new Random();

            //清空图片背景色
            g.Clear(Color.White);

            //画图片的背景噪音线
            for (int i = 0; i < 44; i++)
            {
                int x1 = random.Next(image.Width - i);
                int x2 = random.Next(image.Width);
                int y1 = random.Next(image.Height);
                int y2 = random.Next(image.Height);

                g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
            }

            Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));

            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

            g.DrawString(checkCode, font, brush, 2, 2);

            //画图片的前景噪音点
            for (int i = 0; i < 88; i++)
            {
                int x = random.Next(image.Width);
                int y = random.Next(image.Height);

                image.SetPixel(x, y, Color.FromArgb(random.Next()));
            }

            //画图片的边框线
            g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

            MemoryStream ms = new MemoryStream();
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            return ms.ToArray();
        }
    }
}
